Product keys – or serial numbers if you prefer – are one of the ways software developers protect their products against piracy. When you install a new program, there's a reasonable chance that you'll be asked to enter a serial number to prove that you've paid for it, and over time, you can easily gather a huge collection of programs with their own keys. Some of these keys will be listed in emails, some will be printed on CD cases, and others might be scribbled on scraps of paper.
If you're thinking about formatting your hard drive and start with a clean installation of Windows and all your software, you're going to need all of these codes gathered together in one place before you begin so you can reinstall all your software without any fuss.
The product key viewers in this roundup you can do just that, scouring your hard drive and registry for your serial numbers so there's no need to hunt for them elsewhere. It's a good idea to do this now, because you won't be able to find keys for software that isn't currently installed.
Everything you could ever want to know about your PC in one handy place, including product keys, software versions and hardware stats
Belarc Advisor is primarily a tool for gathering information about your computer hardware and configuration – but it does have extra features on top of this time, including a top-notch product key finder.
Because listing product keys is one of Belarc Advisor's secondary features, you have to wait a while for it to scan your system and determine its hardware and software setup. After that, you'll be shown a page in your default web browser web browser. This isn't because the program has taken you online, but because the information it gathers is displayed in an HTML document. Included in this are details of serial numbers and product keys for Windows, Office and a wide range of other software titles.
Belarc Advisor might not be the most efficient program for simply accessing product keys, but the range of extra auditing features it offers means it's hard to ignore.
Download here: Belarc Advisor
Quickly track down Microsoft product keys and change registered users
Perhaps the most famous of the product key viewers out there, Magical Jelly Bean Keyfinder is still going strong after many, many years.
This is a very simple free product key finder, and it can only provide you with information about your Windows and Office codes – and in the case of more recent versions of both, that's not really necessary. Still, it's good for informational purposes and there are handy extras such as the ability to change the registered owner.
Download here: Magical Jelly Bean Keyfinder
A handy portable app that'll find your Windows product key in seconds
There are no surprises here – Windows Product Key Viewer is a very simple tool that's concerned solely with finding and displaying your Windows product key. No other software is supported, so if you were hoping to create a full inventory for your installed programs, you're going to have to look elsewhere.
Despite its simplicity, Windows Product Key Viewer is still a useful tool, particularly as it is a portable app that you can copy to a USB drive for use on other people's computers. In a matter of seconds, the program will let you know your product key and you can copy this to the clipboard ready to paste in the document of your choosing, or save it directly as a text file. There are no other options offered here, but Windows Product Key Viewer does also let you know how long your computer has been switched on, as well as revealing the exact build number.
Download here: Windows Product Key Viewer
An excellent free product key viewer if you can tolerate the ads
Just like Windows Product Key Viewer, LicenseCrawler is a portable app, so it's a great addition to your USB toolkit and will almost certainly come in handy when you're called upon to help fix someone else's computer.
There's support for a huge number of languages, which gives the tool international appeal, and it's free for personal use, but there's a highly annoying screen that appears when you launch the program that requires you to click a button to continue (and the button changes each time).
LicenseCrawler works by trawling the registry for references to serial numbers, which is a lengthy process. An advert is displayed during the scan, but this disappears after a timer counts down to zero.
Whether you're successful in locating the product key you're looking for really depends on how the software concerned is written, but in our tests LicenseCrawler fared well.
Download here: LicenseCrawler
A free tool that can find product keys for all kinds of software, but bear in mind that the most recent versions might not be supported
As the name implies, MSKeyViewer Plus is chiefly concerned with listing product keys for Microsoft software – and you would think it would end there, but in fact, it can actually let you know the serial numbers for quite a number of non-Microsoft programs too.
Be warned, though – while MSKeyViewer Plus can determine the product key for versions of Windows all the way up to Windows 10, its support for other software is rather more dated. In the case of Office, for example, support stops with Office 2013 and it's only really much older third-party titles that the program can help you with. For example, it supports versions of Winzip up to 14, but the latest release is WinZip 21.
In short, MSKeyViewer Plus is a decent product key finder for Windows, but not if you like to stay right up to date with your other software.
Download here: MSKeyViewer Plus